Acoustical and thermal insulating fibrous glass products have been manufactured for many years. The manufacturing typically involves a process which comprises attenuating the fibers with a rotary device to produce a downwardly falling stream of fibers. During their downward flow, a binder is sprayed onto the glass fibers and the sprayed fibers are collected on a conveyor in the form of a blanket. This blanket is then heated to bind the fibers. Typically, in the past, the binders were thermoset resins such as phenolic resins.
A later development in forming acoustical or thermal insulating glass fiber products is using an asphalt emulsion as the binder. Heating the asphalt coverts the asphalt to an insolubilized form and binds the fibers. An excellent bond results without the use of thermoset resins.
One of the big drawbacks to the use of asphalt as a binder on fiberglass is the cure time required to achieve a high modulus thermoset. The cure of an asphalt based binder is slow in comparison to typical phenolic binders requiring an order of magnitude more time to achieve the same state of cure as measured by recovery of a compressed wool pack.